Partition Help Needed - Desperately

I desperately need some help. I posted this same question on another forum, so hopefully, someone can help.

I won't go into all of the details as to what has happened (and I'm not positive I even know for sure). However, here's what it seems to be tied to... I "Stopped" a running Service yesterday because it was using too much memory (couldn't change it from Automatic to Manual). I knew what the Service was related to (Returnil RVS 2011), and didn't think it would be too much of a problem because I wasn't using that app all the time. However, after Stopping the Service, I noticed a few strange things going on, so I restarted it again.

As a result, it appears that somehow my C:\ partition was cloned and now I have a Z:\ partition, which looks like an exact duplicate of the C:\ partition. This could very well be a temporary or virtual partition, but I have no way of knowing for sure — and it doesn't remove itself, even after multiple reboots.

What do I do?? How do I get rid of the Z:\ partition and get my system back to where it was? I'm using Windows XP SP3